Means for treating steel



Patented Nov. 11, 1942 MEANS FOR TREATING STEEL Samuel Epstein, Bethlehem, Pa", assignor to Bethlehem Steel Company, a corporation of Pennsylvania No Drawing. Application March 11, 1941,

Serial No. 382,741

3 Claims. (6175-129) gen so that the efliciency obtained in adding the This invention relates to means for increasing the nitrogen content of steel to improve its machinability. In the past it has proven to be very diflicult to add anappreciable quantity of nitrogen directly to molten steel due to its relative chemical inertness. Likewise a suitable carrying medium has not been found which would allow sufficient assimilation of the nitrogen by the steel and at the same time not contaminate the steel.

One object of this invention is to facilitate the addition of nitrogen to molten steel.

A second object is to increase the nitrogen content of steel.

Another object is to avoid contamination of the steel by limitng the introduction of any objectionable elements.

Further objects and advantages of this invention will be explained more fully in the follow- .ing detailed description of this invention.

The method employed in this invention to increase the nitrogen content of steel involves the use of an addition agent comprising a finely divided nitrided metal. The nitrided met-a1 may be added to molten steel at any suitable stage, as

for example by adding it to the ingot mold or ladle during the pouring or tapping of the, molten steel. The nitrided metal is produced by sub- .iecting some form of a finely divided metal such as steel wool to a nitriding treatment.

This treatment comprises heating the finely divided metallic material to a temperature between 900 F. and the melting point of the material while subjected for asuitable length of time to the action of ammonia, as for example,

nitrogen was about 30 per cent.

In this invention there are very few limitations to the amount of addition agent that may be used. As a result the possible amount of nitrogen that may be added is extremely high. One factor that often limits the quantity of an addition agent is the production of violent flames objectional elements but also to include desirable elements in the addition agent. In a final analysis, if, for instance, practically pure iron is used in' the finely divided material. there is substantially no limitation placed on the quantity of addition agent other than the ability of the steel to dissolve the added material and to assimil-ate the available nitrogen.

This invention is not restricted to steel wool and trimmings of thin sheet since any source of I I Having thus described my invention what I claim. as new and desire -to secure by Letters Patents is:

1. An addition agent for augmenting the nitrogen content of steel comprising steel wool con- I taining substantially 1 to 10 per cent nitrogen.

dition agent, about 100 pounds of black tin-plate trimmings treated as described above and containing 2% nitrogen were added during pouring .of a full size steel ingot weighing 6000 pounds. The nitrogen in the addition represented 0.033% of the weight of the ingot. The steel was analyzed and found to contain 0.010% nitro- 2.6-.An addition agent for increasing the nitrogen content of ferrous metal'comprising trimmings of black plate of tin plate gauge containing substantially 1 to 10 per cent ofmitrogeh.

3. An addition agent for increasing the nitro- I gen content of ferrous metal comprising a loose expanded mass of elongated fibers of ferrous metal having a high ratio of surface area to volume and' having a nitrogen .content of substantially' 1 to 10 per cent.

- SAMUEL EPSTEIN. 

